Exemplar Questions and Solutions

MCQs

7. Which among the following is (are) double displacement reaction(s)?

i) Pb + CuCl₂ → PbCl₂ + Cu

ii) Na₂SO₄ + NaCl₂ → BaSO₄ + 2NaCl

iii) C + O₂ → CO₂

iv) CH₄ + 2O₂ → CO₂ + 2H₂O

a) (i) and (iv)

b) (ii) only

c) (i) and (iii)

d) (iii) and (iv)

Ans) (b) (ii) Only

8. Which among the following statement(s) is (are) true? Exposure of silver chloride to sunlight for a long duration turns grey due to

(i) The formation of silver by decomposition of silver chloride

(ii) Sublimation of silver chloride

(iii) Decomposition of chlorine gas from silver chloride

(iv)Oxidation of silver chloride

(a) (i) only

(b) (i) and (iii)

(c) (ii) and (iii)

(d) (iv) only

Ans) (b) (i) and (iii)

9. Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form its solution called lime water. Which among the following is (are) true about slaking of lime and the solution formed?

(i) It is an endothermic reaction

(ii) It is an exothermic reaction

(iii) The pH of the resulting solution will be more than seven

(iv) The pH of the resulting solution will be less than seven

(a) (i) and (ii) (b) (ii) and (iii)

(c) (i) and (iv) (d) (iii) and (iv)

Ans) (b) (ii) and (iii)

10. Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of the reaction involved?

(i) Displacement reaction

(ii) Precipitation reaction

(iii) Combination reaction

(iv) Double displacement reaction

(a) (i) only (b) (ii) only

(c) (iv) only (d) (ii) and (iv)

Ans) (d) (ii) and (iv)

11. Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is

(a) 1:1

(b) 2:1

(c) 4:1

(d) 1:2

Ans) (b) 2:1

12. Which of the following is (are) an endothermic process(es)?

(i) Dilution of sulphuric acid

(ii) Sublimation of dry ice

(iii) Condensation of water vapours

(iv)Evaporation of water

(a) (i) and (iii) (b) (ii) only

(c) (iii) only (d) (ii) and (iv)

Ans) (d) (ii) and (iv)